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U.S. EPA issues long-awaited final health assessment for perc, classifies it as a "likely human carcinogen"

For the first time since 1988, the U.S. Environmental Protection Agency (EPA) has updated its health assessment for tetrachloroethylene (more commonly known as perc, and also known as perchloroethylene) by formally classifying the chemical as a "likely human carcinogen" and identifying long-term, noncancer health effects associated with exposure to it. EPA released its final health assessment for perc on February 10, 2012 on the agency's Integrated Risk Information System (IRIS).

Perc is a commonly used dry cleaning solvent. It has also been used as a metal degreaser and in coal processing plants and laboratories. Due largely to releases of perc from dry cleaners, perc is frequently detected in the environment, including in air, soil, groundwater, and drinking water supplies. This has spawned waves of lawsuits by persons whose homes or property have been contaminated with perc. It has also caused some states, such as California, to ban/phase-out the chemical.

EPA's recent classification of perc as a "likely human carcinogen" in the final assessment means that sufficient evidence exists that perc can cause cancer in humans. This is a marked change from EPA's previous designation for perc of "intermediate between a probable and possible human carcinogen." In addition, based on laboratory animal studies, EPA concluded the adverse non-cancer effects from chronic exposure to perc, including harm to the nervous system, reproduction and development, kidney, liver, immune system, and hematologic system, occur at levels well below those estimated when EPA last assessed perc in 1988, reducing the daily exposure limit to a level 6 times lower than the earlier limit.

The implications of EPA's final assessment of perc could be far-reaching, particularly for parties responsible for cleaning up sites contaminated with perc and manufacturers and suppliers of the chemical. Those implications include the following:

EPA's new toxicity values for perc could result in stricter cleanup goals for sites contaminated with perc. This, of course, will make site investigation, assessment, and remediation more expensive and protracted. With respect to Superfund sites, however, EPA will continue to use its maximum contaminant level (MCL) for perc of 5 ppb as the remediation goal for perc-contaminated groundwater, although more stringent perc standards will continue to be used as the cleanup goal in some states (e.g., California). In addition, the current toxicity values will be used to develop cleanup goals for new Superfund sites with indoor air contaminated by vapor intrusion. Interestingly, the cleanup levels for indoor air based on the new toxicity values will actually be less stringent than those previously used, which were based on values set by the California Environmental Protection Agency.

EPA will consider the final assessment in updating its drinking water standard for perc and other carcinogenic volatile organic compounds (VOCs). Given the cancer and noncancer health effects identified in the assessment, it is likely that EPA will lower the standard for perc in an effort to further protect public health. That would require drinking water providers to deactivate and/or treat wells and water supplies impacted by perc at levels that the providers otherwise may have tolerated.

EPA will rely upon the final assessment in reevaluating the National Emission Standard for Hazardous Air Pollutants (NESHAP) for perc, an air emissions standard set by EPA pursuant to the Clean Air Act. EPA's review is expected to begin in 2014. EPA is more likely to impose tighter restrictions on perc air emissions than looser ones based on the health effects findings in the final assessment. Dry cleaners and other perc handlers will be required to install new (and often more costly) equipment in order to achieve compliance with those restrictions.

Manufacturers and importers of perc should consider the need to update their Material Safety Data Sheets (MSDSs), product brochures and bulletins, and other such documents sent to purchasers and users of perc to reflect any new or significant information regarding the chemical's hazard potential contained in EPA's final assessment.

EPA's perc assessment could be a sign of things to come for IRIS reassessments relating to other VOCs that are currently underway, including those relating to methanol, methyl tertiary-butyl ether (MTBE), and ethyl tertiary-butyl ether (ETBE). If the relatively aggressive stance taken by EPA in reclassifying perc as a likely human carcinogen is any indication, EPA may be inclined to reclassify other VOCs if valid scientific evidence regarding carcinogenicity exists.

The plaintiff's bar will no doubt argue that this reclassification strengthens the claims of litigantsand potential litigants arising out of perc contamination. It remains to be seen whether and how this development impacts such matters; however, there is no question that manufacturers and dry cleaning facilities would be well-served to carefully consider the business and litigation exposure implications of EPA's determination.